Pressure differential switch



July 22, l-952 J. M. slMoN 2,604,561 1 PRESSURE DIFFERENTIAL SWITCH Filed Nov. 22, 1948 2 SHEETS- SHEET 1 T0 POWER .SY/PPL? arma/EV July 22, i952 J. M. slMoN 2,604,561

PRESSURE DIFFERENTIAL SWITCH Filed Nov. 22, 194s 2 mms- SHEET 2 Patented July 22, 1952 UNITEDv s'rArss "PATENT OFFICE.

Joseph M. Simon, Los Angeles, Calif. Application November 22, 1948, Serial No. 61,375

1 Claim.

My invention relates to electrical switches and is particularly directed to a pressure differential yswitch for shutting oir the ilow of an electrical current when the pressure, such as oil or other iluids, falls below the desired amount.

My invention is applicable in refrigeration ,plant mechanisms, automobiles, engines and other motors requiring pressure lubrication and in timing X-ray machines. Other uses will be obvious. y

It often happens that the pressure, such as oil pressure in the motor, falls below the desired amount without the operator knowing that it has fallen below that amount. This can result in great damage to the moving parts of the motor through lack of oil.

To guard against this happening, I have provided my present invention, which will makeit limpossible for this to happen.

if the fall in pressure is only momentary or temporary.

Other objects and advantages of my invention will be apparent from the following description and claim, the novelty consisting in the features of construction, combination of parts, and the unique relations of the members and the relative proportioning, disposition and operation thereof, all as more completely outlined herein and particularly pointed out in the appended claim.

In the accompanying drawings, forming a part of this present specification, l

Figure 1 is an elevation of the entire device including the pressure switch element and the timing element.

Figure 2 is a longitudinal vertical section of the pressure switch shown in Figure l.

Figure 3 is a vertical sectional view along lines 3-3 of Figure 2.

Figure 4 is a vertical sectional view along lines 4--4 of Figure 1.

Figure 5 is a vertical sectional view along lines 5-5 of Figure 4.

Figure 6 is a rear View of the timing device, shown in the front view in Figure 1.

' Figure 7 is a plan view ofthe timing device (Cl. ZOO-82) 2. prises a pressure switch element I0 vand a timing element I2.

Referring to the details of these elements, the pressure switch element II), shown vbest in Figures 1 and 2, has a pressure entrance port I4 through which the pressure to be maintained is admitted to the pressure chamber I6. I

Slideably mounted within this pressure chamber I6 is a magnet member I8. The pressure in chamber I6 moves or tends to move the slideable magnet in a direction away from the'pressure entrance port I4. Suitably mounted behind the slideable magnet I8 is the magnet spring 20 which tends to urge the slideable magnet in a direction against the pressure or in an opposite direction to that in which the pressure tends to urge this slideable magnet.

A suitable lower pressure entrance port 2I communicates with the side of slideable magnet I8 opposite to that side of magnet I8 acted upon by pressure from pressure entrance port I4,-and supplements spring 2D in urging slideable magnet I8 in a direction toward port I4. Y K

BelowY the slideable magnet I3 is a rotatable magnet 22, which rotates on a pivot'24. The rotatable magnet 22 is affixed to a mounting 26 which is connected by Va connecting member 28 to a rotating member 30. Thisrotatingkmember 3i) rotates about the pivot 24 with the rotating magnet to which it is integrally attached kby the means described. .y

Also, integrally attached to the rotating'member '30, is a mercury switch 32. Thismercury switch 32 consists of a tube 34, containing a mercury drop 36, which is free to slide along the tube 34 when it is rotated Ain the mannerdescribed presently.

The spring 20 is Vso adjusted that when the desired normal pressure is present in the pressurechamber I6 the balance between the spring -20 and this pressure positions the lslideable magnet I 8 above the rotatable magnet 22 in the position shown in Figure 2 in which the north pole of the slideable magnet IS is above the south pole of the rotatable magnet 2,2 and the south pole of the slideable'magnet I8 is above the `north rpole of `the rotatable magnety 22. In-this position,Y the ypoles opposite each other attract and'cause the rotatable magnet 22 to be attracted land held up as close to the slideable magnet as possible. This causes the rotating member 30,-to rotate about ther pivot24 to the. position shown 'in Figure 2 with the tube 34 slanting so that the mercury drop 36 is at the end of the tube 34 that is distant from the power line contact 38.

When the pressure, entering the pressure entrance port I4 and filling thepressure chamber I6, falls below the desired Iamount the tension of the spring 2U urges the slideable magnet toward the pressure entrance port. When this slideable magnet I8 has moved sufliciently toward the pressure entrance port to break the magnetic attraction between the slideable magnet I8 and the rotatable magnet 22, as for instance, ii the south pole of the slideable magnet is above the south pole of the rotatable magnet, it will cause the rotatable magnet to move away from the slideabie magnet. This will, in turn, cause the rotating member 30, which is integrally attached to the rotatable magnet, to rotate about its pivot 24. When this rotation is sufficient to cause the mercury drop 36 to slide along its tube 34 suiiiciently to contact the power line contact 38, this mercury drop will establish an electrical connection between this power line contact 38, which is connected through a power line 40 to a line 42 to the source of electrical power, and a timing element contact 44, which is connected through a power line 46 to a line 48 to the timing element I2.

This causes electrical power to iiow from the source of electric power along the line 42, power line 40, contact 38, mercury drop 36, timing element contact 44, power line 46, line 48 and power input 50 to the timing element or clock I2. This power then causes the timing element to start working and this, in turn, actuates hand 52 in a counterclockwise direction. The clock also drives shaft 54. A pin 55 is mounted on a sleeve 58 which is keyed to shaft 54. When the clock has run a sufficient time to cause pin 56 to rotate far enough to strike arm 60 on micro-switch 62 and force arm 60 down this breaks a contact inside micro-switch 62, which is not shown. The breaking of this contact cuts ofi all electrical power to whatever device is being driven, such as a motor, the switch of an automobile, etc. The amount of time that it takespin 56 to strike arm 60 depends on the setting hand S4 which is set manually. Figure 8.)

Setting hand 04 is held on bushing 86 by nut 68. Rotation of hand 64 therefore also rotates bushing 6G about shaft 54 in a hole in plate 1D,

which is the main dial face of the clock. Also, f

it rotates a stop 'I2 to the desired position. Bushing 66 has iiat sides to register with a corresponding flat sided hole in stop 12 and hand B4. Thus rotation of hand 64 causes stop I2 and bushing 66 to rotate integrally with hand 64.

Stop I2 holds pin 5S in the desired position from which it starts toward arm 69. Thus, the position of stop I2 determines how long it will be after hand 52 starts before pin 56 strikes arm 69 and lowers it, thus breaking the contact in the circuit and cutting all power off tothe clock and to the motor, such as the ignition switch of an automobile.

When the power to the clock is cut off the tension on spring 'I4 causes hand 52 and pin 55 to return to their original starting position which is determined bythe position of hand 64.

Before the power can be resumed a manually operated pin 'I0 must be pushed to re-establish the power contact in micro switch 62. This means that the operator will have to take care of the cause of the low nuid pressure before he switches on the current again, because the above mechanism will just operate over again if he doesnt, and shut off the power once more.

Thus, to summarize, when the oil pressure, or pressure to be measured, is too low it closes the (See 4 mercury switch 32 and this starts the clock I2, which runs a predetermined time and then shuts oil' the electrical power to the motor.

If the oil pressure, or other pressure to be measured, builds up normally before the electrical current is thus shut oi it will cause the slideable magnet I8 to move against the action of magnet spring 20 to the position shown in Figure 2 where the rotatable magnet 22 is drawn up against or toward the slideable magnet I8. This causes the mercury drop 36 to slide to the other end of the tube 34 and break the contact between power line contact 38 and timing element contact 44. This stops the clock I2 and permits spring I4 to return hand 52 and pin 56 to the starting position and thus the electrical current is not shut from the motor. In this way instantaneous or temporary drops in pressure will not shut oi the electrical current unless they are long enough, determined by the adjustment of the mechanism to the desired interval, to make it advisable to shut olf the electrical current.

Thus, a positive means is provided to shut on? the current if the pressure becomes too low and yet a temporary drop in pressure will not actuate this emergency shut off mechanism provided by my pressure diierential switch.

It is to be understood that the form of my invention herein shown and described is my preferred embodiment and that various changes in the shape, size and arrangement of parts may be resorted to Without departing from the spirit of my invention, or the scope of the appended claim.

I claim:

A pressure differential switch comprising a cylinder, a piston movable longitudinally within said cylinder in response to differences in pressure at opposite ends thereof, said piston constituting a permanent magnet having a north pole at one end thereof and a south pole at the opposite end thereof, a mercury switch mounted for pivotal movement exteriorly of said cylinder, and a permanent bar magnet secured to said mercury switch and positioned adjacent the outer surface of said cylinder with its longitudinal axis generally parallel to said piston whereby in one position of said piston adjacent unlike poles on said piston and bar magnet attract said bar magnet toward said piston and in another position of said piston adjacent like poles on said piston and bar magnet repel said bar magnet from said piston to effect pivotal movement of said mercury switch.

JOSEPH M. SIMON.

REFERENCES CITED The following references are oi.' record in the Iile of this patent:

UNITED STATES PATENTS Number Name Date 1,287,896 Crane Dec. 17, 1918 1,442,311 Watson Jan. 16, 1923 1,442,312 Watson Jan. 16, 1923 1,737,961 Ellis Dec. 3, 1929 1,876,044 Davis Sept. 6, 1932 2,310,261 Schwarzhaupt et al. Feb. 9, 1943 2,335,073 Martin et al Nov. 23, 1943 2,431,674 Baak Dec. 2, 1947 

